In general, this invention is related to a coolant additive composition. More specifically, but not exclusively, this invention is directed to a supplemental coolant additive including anti-corrosion agents for use in cooling systems and to a method of inhibiting corrosion of metal surfaces in cooling systems.
Typically supplemental coolant additives (SCA) are formulated to include specific additives selected to inhibit and reduce corrosion of coolant system components and maintain effective heat transfer. The supplemental coolant additives typically are added to cooling systems in, for example, diesel engines to extend the service life of the coolant and provide additional anti-corrosion protection. Specific formulations are desired because with the advent of higher performance engines, particularly heavy-duty diesel engines, increasing more components of these engines are manufactured from a wide variety of materials to reduce weight and increase engine efficiency. The coolant coursing through these engines contacts the various materials. Typically additives are chosen to impart particular benefits, typically providing protection for one or more selected materials. In addition, it is not uncommon for certain additives to be selected which compliment each other""s properties. Despite the specificity with which these supplemental coolant additives are formulated, the benefits associated with many of the additives can be thwarted because a large percentage of operators include hard water in the cooling system. The hard water can be added either upon initially filling the cooling system or during in-service as operators add make-up water to top off the cooling system.
Furthermore, in warmer climates, water is used in cooling systems to the exclusion of known additives such as ethylene glycol or propylene glycol. In many parts of the world, there is no ready access to suitable water for use in cooling system. Hard water includes a number of minerals, most notably calcium, magnesium and iron salts. These minerals may contribute to loss of efficacy and reduce the usable lifetime of the supplemental coolant additive. This loss can be particularly detrimental to heavy-duty diesel trucks that can cover over 10,000 miles a month. An ineffective supplemental coolant additive can require shorter service intervals, allow internal passageways in the cooling system to clog, contribute to cylinder liner pitting and water pump cavitationxe2x80x94all which result in costly engine overhauls.
Thus in light of the above described problems, there is a continuing need for advancements in the supplemental coolant additives and improved methods for reducing corrosion associated. with cooling compositions. The present invention is such an advancement and provides a wide variety of benefits and advantages.
The present invention relates to novel supplemental coolant additives, the manufacture and use thereof. Various aspects of the invention are novel, nonobvious, and provide various advantages. While the actual nature of the invention covered herein can only be determined with reference to the claims appended hereto, certain forms and features, which are characteristic of the preferred embodiments disclosed herein, are described briefly as follows.
In one form the present invention provides a supplement coolant additive comprising: a corrosion inhibitor component, which includes adipic acid or a salt thereof, a nitrite salt, a molybdate salt and at least one compound selected from the group consisting of: a nitrate salt, a silicate salt, mercaptobenzothiazole, benzotriazole and tolyltriazole; and a buffering agent including a sodium salt of at least one of a borate salt or a phosphate salt.
In another form the present invention provides a supplement coolant additive comprising a corrosion inhibitor component that includes adipic acid or a salt thereof, a nitrite salt, a molybdate salt and at least one of nitrate, silicate, mercaptobenzothiazole, benzotriazole, or tolyltriazole; a buffering agent; and hard water.
In still yet another form the present invention provides a method of reducing the corrosion of metal surfaces in a cooling system having a recirculating liquid coolant comprising hard water. The method comprises adding to the liquid coolant, an anti-corrosion additive including a buffering agent, adipic acid or a salt thereof, a molybdate salt, a nitrite salt, and at least compound selected from the group consisting of: mercaptobenzothiazole, benzotriazole, tolyltriazole, a nitrate salt and a silicate salt.